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Old 10-05-2015, 09:04 AM   #1
foxriderry
 
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Pushrod Length Ls1

Ok so I've been chasing down this sewing machine noise coming from my engine, and decided to check my pushrod length. I measured the intake and exhaust at TDC for each side and came out with 12 turns in on my Comp Cams length checker.
12 turns times 0.05 (<- length of each turn) equals 0.6.
0.6 + 6.8 (<- Length of checker) equals 7.4
7.4 + 0.03 (<- Lifter preload) equals 7.430

Being that 7.430 is longer than stock length I feel like I've done something wrong. The heads where milled, and I installed a Torquer V3 camshaft. I feel like the length should be shorter, can anyone confirm or deny this?

I checked the length by rotating the assembly to pump up the lifters.
Than acquired zero lash and rotated the length checker outward until there was no up and down play in the rocker, only side to side movement. Any help is greatly appreciated.
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Old 10-05-2015, 01:56 PM   #2
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preload is a little low for my liking. LS7 lifters i'm assuming?

but it also depends on the base circle of the cam. not sure what heads you are running but the deck heigh could be different as well

but 12 turns to get to 0 lash is .6" and then you add base length of the tool (6.8" + .6" + the preload to get the pushrod length) so yes you are correct but I just think the preload is low

The lifter preload spec has such a wide range .02-.8 or .9........ Generally you will get slight variations between exhaust and intake. But sounds like you should run a 7.450 to give you .050" preload. (depends on who you ask)

also the cam and lifters you are running can be the cause of some noise.

you are running 7.4 now? basically no preload on the lifters
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Old 10-05-2015, 03:17 PM   #3
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actually running 7.350 so yeah i suck haha.... thought that number was messed up. Nope ls1 lifters. I read their preload was .03 but im happy to take your suggestion.
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Old 10-05-2015, 06:11 PM   #4
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What heads are you running ?

If you had 12 turns and just reached 0 preload and running shorter then 7.4 that's definitely the issue.

I never reused the stock lifter soni don't know what the reccommended preload is.

So you have play in all the rockers with the 7.350's when you are torqued and have a cyl. at TDC ?
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Old 10-07-2015, 02:59 PM   #5
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Sorry for the long reply, Im running 799 heads. I never noticed alot of play in the rockers before i took them off, I know that sounds like a total noob statement haha but ill look further when i get home. I have the #2 cylinder at TDC right now since thats the last one i measured so ill bring up #3 and see what thats like with the untouched pushrods still in there.
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Old 10-07-2015, 04:53 PM   #6
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with #2 at TDC see if you can get any up and down play where the valve stem and rocker touch. it should be the same at all the cylinders based on the measurement.

I was just wondering if you were running after market casting.
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Old 10-08-2015, 01:43 PM   #7
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The heads were milled replaced valve springs and 3 angle valve job, but otherwise they're just regular 799 casting. I wanna look at the untouched cylinder to see if there was alot of play between the 7.350 pushrod and the rocker, i feel like 7.450 is a weird number because its bigger than stock, I thought it would be shorter, although I guess because the cam is larger that would make up the difference? idk im confusing myself
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Old 10-08-2015, 02:31 PM   #8
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I understand. Just ran into a similar issue with an ls2 we did HCI on a vette but used 227 heads.

the guy bought everything through TSP and said 7.4's should work and we needed 7.5's
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Old 10-08-2015, 04:15 PM   #9
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Quote:
Originally Posted by MyFirstZ View Post
I understand. Just ran into a similar issue with an ls2 we did HCI on a vette but used 227 heads.

the guy bought everything through TSP and said 7.4's should work and we needed 7.5's
I wonder who's vette that is....
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Old 10-08-2015, 08:18 PM   #10
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Yeah I meant to ask you about that one lol. I haven't found out the final outcome. All I know is I couldn't be apart of the short term fix
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Old 10-12-2015, 07:57 AM   #11
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few questions, did you measure your installed height? The fact that you've had a vj, has changed that installed height,that combined with the cam, has def altered your pushrod length, myself like you don't run typical preload, I usually hang out at .035 or so give or take a few..you can always grab a caliper and get the exact length of the checker, I've never liked the screw method as there is some slop in tool itself, and it spins very easily..

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Old 10-15-2015, 09:13 AM   #12
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yeah I really dont like the fact that the tool spins so freely, made it hard to get a good measurement.
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